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Asset Retirement Obligations | 9 Months Ended
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Sep. 30, 2023
Asset Retirement Obligation Disclosure [Abstract] |
Asset Retirement Obligations | Asset Retirement Obligations During the nine months ended September 30, 2023, the Company revised its cost estimates for existing Asset Retirement Obligations (“ARO”) for the following: •Cholla coal-fired power plant related to the closure of ponds and facilities, which resulted in an increase to the ARO of approximately $36 million. •Four Corners coal-fired power plant, which resulted in a decrease of approximately $7 million. •Navajo coal-fired power plant, which resulted in an increase of approximately $8 million. •Palo Verde received a new decommissioning study, which resulted in an increase to the ARO in the amount of $33 million, an increase in the plant in service of $34 million and an increase in the regulatory liability of $1 million. APS battery energy storage systems may have asset retirement obligations for the removal of the asset. As of September 30, 2023, no asset retirement obligations have been recorded relating to these types of assets. We are evaluating these asset removal obligations, but do not expect the obligations will be significant. See additional details in Notes 4 and 8. The following schedule shows the change in our asset retirement obligations for the nine months ended September 30, 2023 (dollars in thousands):
| 2023
Asset retirement obligations at January 1, 2023 | $ | 797,762 |
Changes attributable to: |
Accretion expense | 32,763 |
Settlements | (5,750) |
Estimated cash flow revisions | 70,405 |
Asset retirement obligations at September 30, 2023 | $ | 895,180 |
In accordance with regulatory accounting, APS accrues removal costs for its regulated utility assets, even if there is no legal obligation for removal. See Note 4 for detail of regulatory liabilities.

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- Definition The entire disclosure for an asset retirement obligation and the associated long-lived asset. An asset retirement obligation is a legal obligation associated with the disposal or retirement from service of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 410 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481850/410-20-50-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 410 -SubTopic 20 -Name Accounting Standards Codification -Publisher FASB -URI https://asc.fasb.org//410-20/tableOfContent Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name Accounting Standards Codification -Section 50 -Paragraph 2 -SubTopic 20 -Topic 410 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481850/410-20-50-2 + Details
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